US7013053B2 - Polarization independent electro-optical device for modulation of light - Google Patents
Polarization independent electro-optical device for modulation of light Download PDFInfo
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- US7013053B2 US7013053B2 US10/356,778 US35677803A US7013053B2 US 7013053 B2 US7013053 B2 US 7013053B2 US 35677803 A US35677803 A US 35677803A US 7013053 B2 US7013053 B2 US 7013053B2
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/21—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour by interference
- G02F1/225—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour by interference in an optical waveguide structure
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/03—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on ceramics or electro-optical crystals, e.g. exhibiting Pockels effect or Kerr effect
- G02F1/035—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on ceramics or electro-optical crystals, e.g. exhibiting Pockels effect or Kerr effect in an optical waveguide structure
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F2201/00—Constructional arrangements not provided for in groups G02F1/00 - G02F7/00
- G02F2201/12—Constructional arrangements not provided for in groups G02F1/00 - G02F7/00 electrode
- G02F2201/126—Constructional arrangements not provided for in groups G02F1/00 - G02F7/00 electrode push-pull
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F2203/00—Function characteristic
- G02F2203/06—Polarisation independent
Definitions
- This invention is generally in the field of integrated optics and relates to a polarization independent integrated electro-optical device for modulation of light.
- signals are carried within waveguide channels, which are formed by modifying the surface of a substrate.
- the waveguide is optically active, the substrate material is in many occasions anisotropic, usually being a crystal having the ability to rotate the plane of polarization of light passing therethrough.
- Electro-optically active waveguides have electrodes formed in the close vicinity thereof.
- the fundamental phenomenon that accounts for the operation of electro-optic modulators and switches is the change in the index of refraction produced by the application of an external electric field.
- an electric field When an electric field is applied across an optically active medium, the distribution of electric charge within it is distorted so that the polarizability and, hence, the refractive index of the medium changes anisotropically.
- the result of this electro-optic effect may be to introduce new optic axes into naturally doubly refracting crystals, or to make naturally isotropic crystals doubly refracting. In the most general case, this effect is non-isotropic, and contains both linear (Pockels) and nonlinear (Kerr) effects. In commonly used waveguide materials, the nonlinear (quadratic) Kerr electro-optic coefficient is relatively weak.
- an electro-optic crystal will in general exhibit birefringence, if an electric field is applied in a given direction.
- the functional parameters of the devices will depend on the polarization state of the light propagating within the medium.
- Such polarization dependence of functional parameters is one of the main limitations of many integrated optical devices based on substrates of low crystal symmetry.
- practically all the presently installed fiber-optic infrastructures consist of standard single-mode fibers that do not preserve the state of polarization of the transmitted light.
- LiNbO 3 material has a mature technology for the processing of integrated optical devices that is nowadays implemented routinely in commercial products, most of them being, however, polarization dependent. This fact limits the scope of application of this technology to cases where the device is placed directly following a polarized laser source, or alternatively, implies utilization of costly polarization-maintaining fibers in the network.
- the first approach is based on independent electro-optic control of the modulation of both polarizations.
- specific elements of the electro-optic tensor are used for separately modulating TE and TM modes propagating along the waveguide.
- Devices of this kind typically require two independent electrode sets to provide the desired electric field for both TE and TM polarizations.
- the direction of propagation of the waveguide was parallel to the optical axis Z, and the largest electrooptic coefficient r 33 of LiNbO 3 was not used.
- polarization-independent action is obtained at the cost of larger operating voltages or the device's length.
- voltage induced polarization rotation is unavoidable in LiNbO 3 due to the appearance of the r 51 coefficient. This effect causes difficulty in the insertion of such a phase modulator in a Mach-Zehnder scheme.
- the main idea of the present invention is based on the following.
- ⁇ When passing light through a waveguide, different polarizations of an output light signal are associated with different influence of an applied field on the light propagation coefficient, ⁇ .
- Both, ⁇ 2 TE and ⁇ 2 TM are functions of the following variables: an operating wavelength, the orientation of the crystal cut (i.e., the direction normal to the plane where the waveguides are fabricated), the direction of propagation of the wave-guided light, and the location of electrodes relative to the waveguide's axis.
- the latter is associated with certain given parameters of a waveguide-containing structure, such as the thickness of a buffer layer, if any, distance between the electrodes, dimensions of the waveguide, and the refractive index profile.
- the above condition can be achieved for a wide range of operating voltages by properly designing the waveguide-electrode layout of the electro-optic device in accordance with certain given parameters of the device.
- changes of refraction index of a crystal waveguide medium, induced by the application of an external electric field E, can in general be anisotropic.
- Anisotropic nature of the electro-optic tensor signifies that different polarizations will be affected by different elements of the electro-optic tensor.
- the field induced has only y- and z-components, and therefore mainly three electro-optic coefficients, (r 33 r 13 r 22 ), are utilized when designing an electro-optic device with a polarization independent operation.
- a method for designing an electro-optical device for modulation of light having a substantially balanced voltage-phase response in two orthogonal polarization directions wherein the device comprises at least one waveguide channel made in a crystal material and at least two electrodes accommodated at opposite sides of said at least one waveguide channel for applying an external electric field to the waveguide channel, the method comprising the steps of:
- an electro-optical device for modulation of light comprising:
- the present invention is used with a z-cut, x-propagating LiNbO 3 crystal, and is therefore described below with respect to this application.
- an electro-optical device for modulation of light comprising: (a) a waveguide formed from optically active material deployed within at least one waveguide channel, a portion of said waveguide having a central axis of symmetry; and (b) an electrode configuration including at least two electrodes deployed in operative relation to said portion of said waveguide, wherein said at least two electrodes are deployed asymmetrically relative to said central axis of symmetry with at least one of said electrodes overlapping said channel partially such that an actuation voltage applied between said two electrodes results in a substantially equal affect on both TE and TM polarized components of radiation propagating along said waveguide.
- FIG. 1 is a schematic illustration of electrode-waveguide layout in an electro-optical device according to the invention for simultaneous phase modulation of TE and TM waves;
- FIGS. 2 a and 2 b illustrate conventional electrode dispositions for acting on TE and TM modes, respectively;
- FIGS. 2 c and 2 d illustrate configurations of electrodes shifted as to act distinctly on different polarizations of light propagating in a waveguide
- FIGS. 3 a and 3 b are schematic illustrations of an optical field mapping and induced refractive index perturbation for TE and TM polarizations, respectively, in the device of FIG. 1 ;
- FIG. 4 graphically illustrates the dependence of the electrically induced perturbations ⁇ 2 TE and ⁇ 2 TM of TE and TM polarizations, respectively, on the value of the waveguide-electrode layout shift, ⁇ , for a determined value of applied voltage;
- FIG. 5 graphically illustrates a mismatch between TE and TM voltage-induced perturbations, ( ⁇ 2 TM ⁇ 2 TE ), versus the waveguide-electrode layout shift, ⁇ , for different applied voltages;
- FIG. 6 graphically illustrates a mismatch between TE and TM perturbations, ( ⁇ 2 TM ⁇ 2 TE ), versus the waveguide-electrode layout shift, ⁇ , for different buffer layer thicknesses;
- FIG. 7 graphically illustrates error ⁇ / ⁇ 2 versus ⁇ for a certain applied voltage
- FIGS. 8 a and 8 b schematically illustrate an amplitude modulator according to the invention, and a push-pull electrode-waveguide layout thereof for simultaneous control of TE and TM polarizations;
- FIGS. 9 a to 9 c illustrate a number of further configurations of electrodes configured according to the teachings of the present invention to act distinctly on different polarizations of light propagating in a waveguide.
- FIG. 1 there is illustrated a waveguide-electrode transverse cut of an electro-optic modulator 1 , constructed and operated according to the invention.
- the modulator comprises a crystal waveguide 2 coated with an insulating SiO 2 buffer layer 4 having the thickness h, and two electrodes 6 A and 6 B accommodated at opposite sides of the waveguide 2 and spaced from each other a distance b. Both electrodes are positioned in an essentially non-symmetric fashion with respect to the waveguide center.
- the waveguide 2 may be produced by any known suitable technique, for example by in-diffusion of a deposited layer of titanium onto a substrate of lithium niobate.
- any other suitable waveguide can be used, if the proper electro-optic tensor structure is provided.
- the electrode 6 A is shifted from the symmetry center of the waveguide 2 (i.e., from an axis OA of the waveguide 2 ) a certain distance, ⁇ , the purpose of which will be described further below.
- ⁇ the purpose of which will be described further below.
- the use of the buffer layer 4 is optional being aimed at isolating the waveguide from the metal electrodes, thereby reducing power losses in the waveguide.
- the applied voltage difference creates a modulating external electrical field E that has components in the y- and z-directions. Influences of these y- and z-components of the electrical field can be weighted for TE and TM modes in such a way that the effective refractive index changes induced by the electrodes on the waveguide are identical for both polarizations.
- n o , n e are refractive indices of LiNbO 3 substrate for y- and z-directions, respectively
- ⁇ n 1 TE and ⁇ n 1 TM are the changes in the refractive indices of TE and TM light components, respectively, caused by in-diffusion of titanium (this factor takes into account anisotropy caused by differences in the diffusion constants in both axis)
- ⁇ n 2 TE and ⁇ n 2 TM are the perturbations in the refractive indices of TE and TM light components
- the small correction 0(r 42 ) corresponds to slight rotation of the principal axes induced by the external electric field. These terms will induce coupling between the TE and TM modes.
- Lithium Niobate is characterized by the large material birefringence. Therefore, the large phase velocity mismatch between the TE and TM modes makes TE ⁇ TM conversion negligibly small in this case (typically less than 10 ⁇ 4 ).
- the coefficient r 33 is about three times larger than the coefficient r 23 and ten times larger than the coefficient r 22 .
- FIG. 2 a and 2 b illustrate the z-cut crystal with the waveguide 2 directed along the x-axis, showing, respectively, the TE- and TM-configurations of electrodes 6 , the net polarization being entirely in the y- and z-direction.
- the propagation constants of the waveguide mode can be divided into approximately three contributing parts, that is: ⁇ TE ⁇ k 0 n o + ⁇ 1 TE + ⁇ 2 TE ⁇ TM ⁇ k 0 n e + ⁇ 1 TM + ⁇ 2 TM wherein: ⁇ 1 TE and ⁇ 1 TM are the contributions of TE and TM modes, respectively, to propagation constant as a result from the diffusion of Ti (solving the modal equation for the two first terms in the above equations for ⁇ n 1 TE and ⁇ n 1 TM ); and ⁇ 2 TE and ⁇ 2 TM are the added perturbations each depending on the voltage-induced changes in the corresponding refractive index ( ⁇ n 2 ).
- the mapping was performed by finding the distribution of charges in the electrodes 6 A and 6 B, followed by summation of the contributions of each charge segment to the total electric field at each point. This technique is known, being disclosed, for example, in the following documents:
- the index perturbation for each polarization was computed via the tensor relationships implied in the above equations for ⁇ n 2 TE and ⁇ n 2 TM .
- calculation of the unperturbed modes was performed by means of a known BPM-based method disclosed, for example, in the following documents:
- FIG. 4 showing two graphs R 1 and R 2 corresponding, respectively, to the dependence of ⁇ 2 TE and ⁇ 2 TM on the value of electrode-waveguide layout shift ⁇ .
- the device simultaneously modulates TE and TM signals with identical voltage-phase efficiencies.
- FIG. 5 shows six graphs G 1 –G 6 corresponding to the difference in voltage perturbations between the two modes for six different values of bias voltages, respectively.
- FIG. 7 illustrating the lithography tolerances required for a balanced TE ⁇ TM operation
- a graph H shows the relative difference in induced phase ( ⁇ / ⁇ 2 ) as a function of the error in displaced ⁇ .
- the polarization dependency in phase modulation, ⁇ / ⁇ 2 can be controlled to be less than ( ⁇ 13) dB.
- the polarization-independent phase modulation is achieved by properly designing the electrode layout.
- FIGS. 8 a – 8 b illustrating an amplitude modulator 10 having a push-pull electrode-waveguide layout.
- the modulator 10 comprises two pairs of shifted electrodes 12 A– 12 B and 14 A– 14 B with respect of two waveguide channels 16 and 18 .
- the modulator 10 allows for change in sign of ⁇ 2 in both arms I and II (waveguide channels), and, correspondingly, for doubling the phase difference accumulated for a single operating voltage. As shown, a symmetrical disposition of the electrode shift reverts both the z- and y-components of the electrical field E. As shown, in the amplitude modulator 10 two waveguides are joined at the extremes to form Y-junctions, which is the basic requirement for amplitude modulation.
- the novel layout in waveguides fabricated on z-cut, x-propagating LiNbO 3 crystals provides essentially polarization-independent amplitude modulation.
- the device according to the invention utilizes a single voltage source to provide the required electric field control for polarization independent operation.
- Polarization independence of an electro-optical modulator can be achieved due to the provision of an appropriate electrode-waveguide layout, i.e., appropriate shift of the electrodes from the axis of the corresponding waveguide channel at a predetermined thickness of a buffer layer.
- This electrode-waveguide layout could be in principle applied to other integrated optical devices, e.g., active couplers.
- FIGS. 9 a – 9 c it should be noted that the fundamental principle of the present invention, namely, to provide an electrode configuration in which a single activation voltage inherently acts substantially similarly on both TE and TM modes, can be implemented with a range of different electrode configurations.
- three additional configurations for phase modulation will now be illustrated with reference to FIGS. 9 a – 9 c.
- FIG. 9 a shows an electrode configuration in which a pair of electrodes 54 a and 54 b are deployed at an angle to the extensional direction of the underlying waveguide 52 .
- This electrode configuration provides a transition (from left to right) from electrodes of the TE type to electrodes of TM type.
- the magnitude of the effect of the modulating voltage V m on each of the two polarization types depends upon a number of factors, including the dimensions of the electrodes and the angle formed between the direction of the waveguide and the extensional direction of the electrodes. These parameters are chosen such that a single actuation voltage applied between the electrodes results in substantially the same phase modulation effect on each polarization mode.
- FIG. 9 b shows a further configuration in which a pair of electrodes 56 a and 56 b are subdivided into two parts along their length as measured parallel to the extensional direction of waveguide 52 .
- the electrodes provide a TE type electrode configuration
- a second region 58 b they provide a TM type electrode configuration.
- the two sections of each electrode 56 a and 56 b are interconnected, preferably directly by an appropriately formed transition region conductor to form two contiguous electrodes as illustrated.
- the magnitude of the effect that the modulation voltage has on the phases of the two polarizations depends upon various parameters, including the lengths of the two sections.
- the electrode configuration provides the required essentially balanced effect.
- FIG. 9 c it should be noted that configurations such as those of FIGS. 9 a and 9 b have advantages in providing the possibility of “tuning” of the modulator to provide the desired effect by “electrode trimming”.
- the geometrical design of the electrodes and waveguides are determined by calculation or simulation modeling, and then implemented by use of a photolithography mask or set of masks to produce the optical modulator or switch using basically standard microelectronics techniques. Due to imperfections in the process or materials used, the balance in the modulation of the two polarizations in the final product may be sub-optimal. After characterizing the performance of the device, the length of each section can be suitably shortened by trimming its length.
- trimming process can be repeated until the measurements exhibit balance between the effects on the two polarization components to a predefined degree of accuracy. Trimming of the electrode may be performed by various known techniques, such as by chemical etching or pulsed laser irradiation.
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Abstract
Description
where i=1,2,3,4,5,6 and where j=1,2,3 are associated with X,Y,Z respectively, the 6×3 matrix [rij] being the electro-optic tensor.
β2 TE−β2 TM=0
wherein β2 TE and β2 TM are changes in the propagation coefficients of TE and TM light components, respectively, caused by the applied field. Both, β2 TE and β2 TM are functions of the following variables: an operating wavelength, the orientation of the crystal cut (i.e., the direction normal to the plane where the waveguides are fabricated), the direction of propagation of the wave-guided light, and the location of electrodes relative to the waveguide's axis. The latter is associated with certain given parameters of a waveguide-containing structure, such as the thickness of a buffer layer, if any, distance between the electrodes, dimensions of the waveguide, and the refractive index profile.
wherein (1/n2) now denotes the tensor representing the entire index ellipsoid after the application of an electric field; no and ne are refraction indices for, respectively, ordinary (TE) and extraordinary (TM) polarization components; Ex, Ey and EZ are, respectively, x-, y- and z-components of the external electric field. Utilizing a z-cut crystal material, and an x-propagating waveguide, the field induced has only y- and z-components, and therefore mainly three electro-optic coefficients, (r33 r13 r22), are utilized when designing an electro-optic device with a polarization independent operation.
-
- (a) providing a predetermined orientation of the plane of propagation of light in the crystal;
- (b) providing a predetermined direction of propagation of the light within said at least one waveguide;
- (c) providing a desired electrodes-waveguide layout by shifting said at least two electrodes from an axis of the waveguide channel a predetermined distance in a certain direction, the desired shift being such that, for given values of an operating wavelength and certain parameters of the device, said substantially balanced voltage-phase response of the device is provided substantially irrespective of the applied voltages.
β2 TE=β2 TM=0
wherein β2 TE and β2 TM are changes in the propagation coefficients of, respectively, TE and TM light components induced by the application of the external electric field created by applying a voltage difference between the electrodes.
-
- (i) at least one waveguide channel made within a crystal material of a predetermined orientation of the plane of propagation of light therein and directed in a predetermined direction; and
- (ii) at least two electrodes accommodated at opposite sides of said at least one waveguide channel for applying an external electric field to the waveguide channel,
- wherein a predetermined electrode-waveguide layout is provided by shifting said at least two electrodes relative to the axis of the waveguide channel a predetermined distance in a certain direction, wherein said predetermined electrode-waveguide layout is such that, for given values of an operating wavelength and certain parameters of the device, said substantially balanced TE−TM voltage-phase response of the device is provided irrespective of the applied voltages
n TE(y,z)≈n o +Δn 1 TE(y,z)+Δn 2 TE(y,z)
n TM(y,z)≈n+Δn 1 TM(y,z)+Δn 2 TM(y,z)
wherein: no, ne are refractive indices of LiNbO3 substrate for y- and z-directions, respectively; Δn1 TE and Δn1 TM are the changes in the refractive indices of TE and TM light components, respectively, caused by in-diffusion of titanium (this factor takes into account anisotropy caused by differences in the diffusion constants in both axis); Δn2 TE and Δn2 TM are the perturbations in the refractive indices of TE and TM light components, respectively, caused by electrostatic field E having the explicit form:
Here, averaging is made over the entire waveguide mode. Since for the TE-configuration of electrodes (
r 22 −r 32≠0
r 33 −r 23≠0
The relative sign of these two expressions will dictate whether the sign of the electrode shift Δ will be positive or negative, as shown in
βTE ≈k 0 n o+β1 TE+β2 TE
βTM ≈k 0 n e+β1 TM+β2 TM
wherein: β1 TE and β1 TM are the contributions of TE and TM modes, respectively, to propagation constant as a result from the diffusion of Ti (solving the modal equation for the two first terms in the above equations for Δn1 TE and Δn1 TM); and β2 TE and β2 TM are the added perturbations each depending on the voltage-induced changes in the corresponding refractive index (Δn2). From the Variation Theorem, this consideration is evaluated by means of:
wherein the functions UTE(y,z) and UTM(y,z) are the respective mode functions found by solving the waveguide modes without the presence of an external field.
Δβ=β2 TE(λ,h,ΔV,−Δ)β2 TM(λ,h,ΔV,Δ)=0
wherein λ is the operating wavelength, Δ is the electrode shift from the symmetry center of the unperturbed guide, and h is the thickness of the insulating SiO2 buffer layer.
-
- S. Ramo et al., “Fields and Waves in Communication Electronics”, John Wiley & Sons, 2nded, 1984;
- O. G. Ramer, “Integrated Optic Electrooptic Modulator Electrode Analysis”, IEEE Journal of Quantum Electronics, vol. QE-18, No. 3, pp. 386–392, 1982
- D. Marcuse, “Optimal Electrode Design for Integrated Optics Modulators”, IEEE Journal of Quantum Electronics, vol. QE-18, No. 3, pp. 393–398, 1982.
-
- M. D. Feit et al., “Comparison of calculated and measured performance of diffused channel-waveguide couplers”, J. Opt. Soc. Am., vol. 73, No. 10. Pp. 1296–1304, 1983;
- Y Chung, N. Dagli, “Explicit finite difference beam propagation method application to semiconductor rib waveguide Y-junction analysis”, Electron. Lett., vol. 26, No. 11, pp. 711–713, 1990.
-
- 1. Direct application of the Variation Integral in the above equations;
- 2. Application of the same BPM-based method, now to the combined Ti-in-diffused and voltage-perturbed guides.
Claims (13)
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US8279511B2 (en) * | 2008-07-11 | 2012-10-02 | University Of Florida Research Foundation, Inc. | Method and apparatus for modulating light |
CN102033334B (en) * | 2010-12-14 | 2012-07-11 | 江汉大学 | Electro-optic modulator based on gamma 51 and realization method |
JP5983256B2 (en) * | 2012-09-28 | 2016-08-31 | 住友大阪セメント株式会社 | Light modulator |
CN104142585A (en) * | 2013-05-09 | 2014-11-12 | 鸿富锦精密工业(深圳)有限公司 | Electrooptical modulator |
CN106170732B (en) * | 2014-02-18 | 2019-10-01 | 弗劳恩霍夫应用研究促进协会 | Polarize unrelated formula electric light induction waveguide |
CN109976001A (en) * | 2019-04-22 | 2019-07-05 | 中国电子科技集团公司第四十四研究所 | The multi-channel high-speed electrooptic modulator of high-isolation |
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US4262994A (en) * | 1980-01-11 | 1981-04-21 | Sheem Sang K | Electro-optically balanced multi-piece optical waveguides |
US4291939A (en) * | 1978-03-24 | 1981-09-29 | The United States Of America As Represented By The Secretary Of The Navy | Polarization-independent optical switches/modulators |
US4691984A (en) * | 1985-09-26 | 1987-09-08 | Trw Inc. | Wavelength-independent polarization converter |
US4818063A (en) * | 1985-03-15 | 1989-04-04 | Nippon Hoso Kyokai | Optical modulating/switching device |
-
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Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4291939A (en) * | 1978-03-24 | 1981-09-29 | The United States Of America As Represented By The Secretary Of The Navy | Polarization-independent optical switches/modulators |
US4262994A (en) * | 1980-01-11 | 1981-04-21 | Sheem Sang K | Electro-optically balanced multi-piece optical waveguides |
US4818063A (en) * | 1985-03-15 | 1989-04-04 | Nippon Hoso Kyokai | Optical modulating/switching device |
US4691984A (en) * | 1985-09-26 | 1987-09-08 | Trw Inc. | Wavelength-independent polarization converter |
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